Rename Matrix3::look_at_[rh|lh] to look_to_[rh|lh]

This makes the Matrix3/4 and Decomposed `look_at_*` functions consistent
with looking at a center/focus point and `look_to_*` functions consistent
with looking in a direction.

Author: aloucks

src/matrix.rs

@@ -189,7 +189,7 @@ impl<S: BaseFloat> Matrix3<S> {
 
     /// Create a rotation matrix that will cause a vector to point at
     /// `dir`, using `up` for orientation.
-    #[deprecated = "Use Matrix3::look_at_lh"]
+    #[deprecated = "Use Matrix3::look_to_lh"]
     pub fn look_at(dir: Vector3<S>, up: Vector3<S>) -> Matrix3<S> {
         let dir = dir.normalize();
         let side = up.cross(dir).normalize();
@@ -200,7 +200,7 @@ impl<S: BaseFloat> Matrix3<S> {
 
     /// Create a rotation matrix that will cause a vector to point at
     /// `dir`, using `up` for orientation.
-    pub fn look_at_lh(dir: Vector3<S>, up: Vector3<S>) -> Matrix3<S> {
+    pub fn look_to_lh(dir: Vector3<S>, up: Vector3<S>) -> Matrix3<S> {
         let dir = dir.normalize();
         let side = up.cross(dir).normalize();
         let up = dir.cross(side).normalize();
@@ -210,12 +210,8 @@ impl<S: BaseFloat> Matrix3<S> {
 
     /// Create a rotation matrix that will cause a vector to point at
     /// `dir`, using `up` for orientation.
-    pub fn look_at_rh(dir: Vector3<S>, up: Vector3<S>) -> Matrix3<S> {
-        let dir = -dir.normalize();
-        let side = up.cross(dir).normalize();
-        let up = dir.cross(side).normalize();
-
-        Matrix3::from_cols(side, up, dir).transpose()
+    pub fn look_to_rh(dir: Vector3<S>, up: Vector3<S>) -> Matrix3<S> {
+        Matrix3::look_to_lh(-dir, up)
     }
 
     /// Create a rotation matrix from a rotation around the `x` axis (pitch).
@@ -1135,12 +1131,12 @@ impl<S: BaseFloat> Transform<Point3<S>> for Matrix3<S> {
 
     fn look_at_lh(eye: Point3<S>, center: Point3<S>, up: Vector3<S>) -> Matrix3<S> {
         let dir = center - eye;
-        Matrix3::look_at_lh(dir, up)
+        Matrix3::look_to_lh(dir, up)
     }
 
     fn look_at_rh(eye: Point3<S>, center: Point3<S>, up: Vector3<S>) -> Matrix3<S> {
         let dir = center - eye;
-        Matrix3::look_at_rh(dir, up)
+        Matrix3::look_to_rh(dir, up)
     }
 
     fn transform_vector(&self, vec: Vector3<S>) -> Vector3<S> {

tests/matrix.rs

@@ -728,10 +728,10 @@ pub mod matrix3 {
     }
 
     #[test]
-    fn test_look_at_lh() {
+    fn test_look_to_lh() {
         let dir = Vector3::new(1.0, 2.0, 3.0).normalize();
         let up = Vector3::unit_y();
-        let m = Matrix3::look_at_lh(dir, up);
+        let m = Matrix3::look_to_lh(dir, up);
 
         assert_ulps_eq!(m, Matrix3::from([
             [0.9486833, -0.16903085, 0.26726127],
@@ -744,10 +744,10 @@ pub mod matrix3 {
     }
 
     #[test]
-    fn test_look_at_rh() {
+    fn test_look_to_rh() {
         let dir = Vector3::new(1.0, 2.0, 3.0).normalize();
         let up = Vector3::unit_y();
-        let m = Matrix3::look_at_rh(dir, up);
+        let m = Matrix3::look_to_rh(dir, up);
 
         assert_ulps_eq!(m, Matrix3::from([
             [-0.9486833, -0.16903085, -0.26726127],